Charge forming device



E. J. BARR CHARGE FORMING DEVICE Filed Feb. 5, 1962 Aug. 17, 1965 IN VEN TOR.

M@ WHA/VN a CMAN/GAL f/orneys for Alalai/'cani United States Patent O Middle CHARGE FUER/ENG Dill/TEE Edward y. Barr, Torrance, Calif., assigner tn McCulloch Corporation, Los Angeles, Calif., a corporation of Wisconsin Filed lich.. 5, i962, Ser. No. 179533 3 Stalins. (Cl. 2in1- 43.)

This invention relates to fuel feeding systems for internal combustion engines and more particularly to devices or systems in which liquid fuel is supplied thereto under super-atmospheric pressure.

While the invention has particular utility in connection with two-cycle internal combustion engines, and is disclosed herein in such connection, it is to be understood that its utility is not coniined thereto.

There are various problems and dilliculties involved in the provision of a carburetor or fuel supply system for two-cycle internal combustion engines which will provide the proper fuel mixture under various operating conditions of the engine, and it is an object of the present invention to provide a fuel system or carburetor or charge forming device that will solve these problems and overcome said difiiculties.

It is another object of the invention to provide a charge forming device of this character wherein the fuel-air ratio remains constant.

lt is still another object of the invention to provide a deviceof this character wherein there is instantaneous response of the system to changes in air flow to thereby maintain the fuel-air ratio constant.

. It is a further object of the invention to provide a device of this character utilizing mass air iiow, thereby providing a sound metering system.

It is another object of the invention to provide a device of this character wherein there is a smooth transition from idling to normal operation.

It is still another object of the invention to provide a device of this character wherein flat spots are eliminated.

It is a further object of the invention to provide a charge forming device or carburetor of thischaracter wherein spit-back from the air horn is eliminated.

it is a still further object of the invention to provide a device of this character wherein there is a boost to the discharge of fuel with opening movement of the throttle valve from the idle position.

It is another object of the invention to provide a system or device of this character having a signal system controlling discharge of fuel, said signal system being responsive to pressures in predetermined locations in the induction passage.

lt is a` still further object of the invention to provide a device or system of this character having a primer which will not only provide a fuel required for starting but also fills the fuel passages of the device so that there will be no possible interruption of the supply of fuel after the engine has started.

It is another object of the invention to provide a device or system of this charatcer having a novel venturi.

It is still another `object of the invention to provide a device or system of this character having improved signal characteristics.

it is a further object of the invention to provide a device or system of this character having improved airflow characteristics and wherein more air will flow therethrough.

It is a still further object of the invention to Aprovide a device of this character that is extremely compact.

lIt is still another object ofthe invention to provide a simplified device of this character which may be built at reasonable cost` and which is capable of accurately dlgd Patented Aug. l?, 1965 The characteristics and advantages of the invention are further sufficiently referred to in connection with the following detailed description of the accompanying drawing, which represents one embodiment. After considering this example, skilled persons will understand that many variations rnay be made without departing from the principles disclosed and I contemplate the employment of any structures, arrangements, or modes of operation that are properly within the scope of the appended claims.

Referring to the drawing, which is for illustrative purposes only: l

FlG. 1 is a schematic sectional view showing a carburetor or fuel supply system, or charge forming device, embodying the present invention;

FIG. 2 is a reduced front view of the venturi insert; and

FlG. 3 `is a rear view of said insert.

Referring more paiticularly to the drawing, the device comprises a body lil having an induction passage therethrough which includes an air-inlet portion or section l2 and an air-fuel mixing section or chamber 14 having a mixture outlet 16 adapted to be connected 'to the mixture inlet of the engine in the usual well known manner.

Control of the fluid ilow through the induction passage is effected by a throttle valve 17 of the usual butterfly type mounted on a throttle shaft 13 which extends across the induction passage and has end portions journaled in the walls of the body itl. Throttle shaft 18 is provided with a throttle layer, not shown, connected to suitable actuating mechanism of any well known type.

At the air-inlet end of the induction passage there is means defining, with the adjacent portions of the induction passage wall, a venturi, said means comprising an insert indicated generally at 2li. This insert comprises a hollow elongated body portion 21 having a curved inward taper terminating in a rounded end 20a, the: body 21 presenting a streamlined exterior with the smaller end 2da within the induction passage and the larger end spaced outwardly of the air-inlet opening 22 of the air-inlet section l2. The outer end of the body 21 curves outwardly at 23 and merges with a iiange, indicated generally at 24, extending radially outwardly. Flange 24 is generally circular but is offset from the axis of the body 21 and hence is eccentric relative to said body. Consequently flange 24- is wider at one side, as indicated at 2S, than it lis at the diametrically opposite side 26.

Means for positioning the insert 2t) within the induction passage is provided and comprises a plurality of vanes, there being three vanes provided and indicated by respective reference numerals 2S, Z9 and 3d. These vanes run lengthwise of the insert and, hence, lengthwise of the induction passage and are annularly spaced apart substantially 120, as best shown in FIG 3. However, any suitable arrangement of vanes may be used'.

The diameter of flange 1M is somewhat greater than the diameter of the inlet 22 of the induction passage and the outer end portions 28a, 29u and Stia of the vanes extend outwardly of the plane of the inner wall of the induction passage.` A major portion of each vane extends within the induction passage and the respective varies have outwardly rounded shoulders 281'), 2% and 3d!) which abut against the correspondingly rounded outer end of the air-inlet section to thereby space theilange 24 outwardly of the adjacent wall of the body l@ to provide inlet air flow passage means. Since the insert Ztl is eccentrically disposed within the induction passage, the offsetting of the axis of said insert relative to the axis of the induction passage being downwardly, the inlet air passage aceros@ means at the upper side of tire induction passage, the purpose of this arrangement being described more particularly hereinafter.

Any suitable means may be used to secure the insert in the induction passage. However, the means used comprises a screw, not shown, disposed in a tapped opening in the adjacentpart of the body liti, said screw extending through a peripheral notch in the flange 2d of the insert yand aV portion of the body thereof, as best shown in FIGS. 2 and 3. The head of the screw overlies a portion of the flange 24 at the edge of the notch .2i-t and thereby holds the insert in position in the induction passage.,

At the inner end of the insert there is a throttle valve stop which extends from the inner end of the insert toward the throttle valve and projects into the path of movement of an edge portion of said valve, as best shown in FIG. l. The various parts of the insert are shown as being integral although these parts could be separate elements which are secured together by any suitable means. Y

The body l@ includes a shallow recess dii defined by a top wall 41 and anannular wall 42 normal to the top wall 4l. A flexible diaphragm i3 substantially parallel to the wall 4l closes the open end of the recess if? to thereby define a pressure f uel chamber, said diaphragm being marginally clamped between the annular wall i2 and the upper end or edge, as shown in FIG. l, 0f an annular wall '44 of an intermediate plate, indicated generaily at 45', which has an upper recess d6 and a lower recess 47 separated by a partition Wall 48. F'rexible diaphragm 43 serves as a movable wall separating the pressure fuel chamber from the chamber de, the latter being vented to atmosphere by means of a vent passage Si) so that said chamber do may be termed an atmospheric chamber, since atmospheric pressure prevails therein.

Recess 47 has its open lower end closed by a flexible diaphragm 52 which is marginally clamped between the lower free end or edge of an annular flange Se of the intermediate plate and the upturned annular iiange 55 of an outer plate ory cap, indicated generally at Se, having a'bot'tom Wall 5'7 from which Asaid annular fiange 54 extends. The intermediate plate 45 and the cap 56 are -secured to the body 1i? by any suitable means, such as, for example, screws, not shown.

A Chamber 47 is a signal sensing chamber, while the chamber 5d defined by the cap Se and diaphragm 52 is anY atmospheric chamber which is vented to atmosphere by means of a vent passage 59 so that atmospheric pressure prevails in the chamber Diaphragm 43 may be termed the wet diaphragm since it comprises one wall of the fuel chamber iti and is eX- posed on its upper side, as shown in FIG. 1, to the fuel in chamber dfi. Diaphragm 52 is termed the dry diaphragm or sensing diaphragm. V i

Diaphragm reinforcing plates dii and 61 are disposed on the top and bottom sides of the diaphragm 43 and are secured in position by any suitable well known manner. It is to be noted that the plates 6@ and 6l are of substantially smaller diameter than the diaphragm i3 and are axially arranged on the diaphragm 43 Vand secured together with a central portion of said diaphragm between said plates.

Diaphragm 52 is provided with similar plates 62 and 63 and there is an operable connection between said diaphragms, said connection comprising a pin 65 slidably disposed in the -partition wall 48 of the intermediate plate 45. The top and bottom ends respectively of the pin 65 are in engagement with the plates 6l and 62, so that upward movement of the diaphragm 52 will effect a corresponding movement of the diaphragm 43 and downward mov-ement of said diaphragm i3 will effect a corresponding movement o'f the diaphragm 52.

. Fuel is supplied to the fuel chamber d@ by means of apump, indicated generally at 7d, said pump being of any suitable character but being shown as a pulse pump of well known type. The pump has a fuel chamber 71 formed in the body l@ and closed at its outer side by a exible pump diaphragm 72. which is marginally clamped between portions of the body about the chamber 7l and a cover 73. riihe latter has a pulse chamber '7d formed in the under side thereof opposite the fuel chamber 7l, said pulse chamber being closed at its under or open side by the diaphragm 72 so that said diaphragm is responsive to pulsations in the chambers 7d. In order to provide pulsations in chamber 74 there is a conduit or passageway '75 which is connected to the crankcase 70a of a two-cycle engine.

Fuel chamber 71 is connected to a suitable source of fuel by means of inlet passageway means 76 and '77, the latter terminating at its downstream end in a filter chamber 78 formed in the cover 7?. The passageway 76 has one end connected with the fuel chamber 7l and the opposite end connected with a lter chamber 79 in the body lf? in alignment with the filter chamber '78, there being a filter dd Adisposed in a recess provided therefor in the cover 73, said filter Si? being disposed between the filter chambers 73 and 79 for filtering the fuel passing from the inlet passage 77 to the inlet passage 76. A check valve Si is disposed in the passageway '76 and permits fuel to enter the fuel chamber V'7l but prevents reverse flow of fuel through said passage 76.

Fuel is discharged from the pump by way of a conduit S2. which has a connection with a valve chamber S3 in which is operably disposed a movable valve member d4 having a conical tip 85 controlling the inlet port 36 of the valve'chamber S3. ConduitvSZ has a check valve 32a therein permitting fiow to said valve chamber but preventing reverse flow through said conduit SZ.

Means for controlling the fuel valve 34 is provided and includes a lever S7 having a U-Shaped part SS intermediate its ends, said part fi being disposed on a pivot S9 in a recess 9i) in the upper wall of the fuel chamber 40. Lever 87 includes a part 91 engaging the top plate d@ of the wet or fuel diaphragm 43. The opposite end portion 92 of the lever 57 engages a lower end of the fuel valve E24 and there is a spring 93 dispose-d in a recess 94 in the top wall of the chamber d@ which yieldingly urges the lever S7 in a clockwise direction and, hence, urges the valve S4 in the closing direction.

There is a main fuel discharge orifice or port '96 located between the venturi formed by the insert 24D and the throttle valve 17, said orifice being connected to the fuel chamber ffii by means of a fuel passage 97, a needle valve chamber 98 and a fuel passage 99, said needle valve chamber 93 being disposed between the passages 97 and 99.

An adjustable orifice ldd is provided between the passages 97 and 99 at the entrance to the passage 99, the sides of orifice ffii? being'controlled by a needle valve fill threadably disposed in a tapped bore liti?. provided therefore in the body lid, said valve Mill having a conical tip w3 which extends into the orifice Miti. rEhe opposite end of the valve llfill extends outwardly of the body it) and is provided with an enlarged head ldd having a slot therein for reception of a tool whereby the valve itil may be rotated to variably position the tip N3 and thereby determine the size of the orice Miti.

The carburetor alsoincludes a secondary fuel system which includes a passage MP5' from the fuel chamber it? to a needle valve chamber file. rflie'latter is provided withan orifice M7 communicating with a pair of passages llfii Vand 1%', passage ljii terminating in an idle port il@ disposed downstream of the adjacent or lower edge of the `throttle valve f7 when the latter is in the closed position. Passage 1&9 terminates at its downstreamend in a midrange port lll disposed between the said adjacent or lower edge of the throttle Valve 17 when the latter is closed and the main fuel port 95. Idle port 1l@ isclose to the trailing edge of the throttle valver 117V when the latter is Vin the closed position, the midrange port lll being spaced somewhat further from the said edge of the throttle valve when in the closed position than the port 11G.

The size of orifice HB7 is adjustable by means of a needle valve M2 disposed in a tapped bore 114 provided therefor in the body lil. Valve M2 is provided with a conical tip M5 which is adjustable inwardly and outward- Ily of the orifice lil? to vary the size thereof, the outer `end of valve 112 being provided with an enlarged head 116 disposed outside of the body it), said head ile being slotted to provide means for engagement by a suitable tool for actuating said valve and to thereby vary the size of the orifice 107.

Signal sensing chamber d'7 has a sensing connection With the 'throat l2@ of the venturi defined by the insert -body portion 21 and the adjacent Wall of the induction passage, said connection comprising a conduit 121 having one end connected with said sensing chamber d'7 and the opposite end connected With a port M2 at the throat i120 of said venturi.

When the throttle valve 17 is in the idle position, as shown in FIG. l, fuel for idling is discharged from the idling port lit] which is at the engine side of the throttle valve, such discharge of fuel for engine idling is eected While the `liquid regulator, including the Wet diaphragm 43, is under a sub-atmospheric condition. At this time, as the idling fuel is being discharged from the port llltl, air is bled to the idling fuel passage 103 from the midrange port lill which is at the atmospheric side of the throttle valve when the latter is in the idling position. The strength of air-to-fuel ratio of the idling fuel mixture is determined by the adjustment of the needle valve 112. When the throttle valve is in the idling position the dry regulator, which includes the diaphragm 52, is not functioning.

As the throttle valve i7 is initially moved from the idling position to expose the port lll to suction from theiengine, there is a very loW air tiow condition so that there is no signal at the port 12.2, fuel being discharged from the port llt) and lll to take care of the idling of the engine and the midrange transition as the throttle valve is moved further in the opening direction.

Upon such further opening movement of the throttle valve the engine speed increases accordingly so that there is an increase in air flow through the induction passage. This increase in air flow is sensed by the port 12,2 and the signal thus sensed is transmitted to the signal sensing or pressure chamber 47 to thereby eifect upward movement of the dry diaphragm 52. Upward movement of the diaphragm 52 is simultaneously transmitted through the pin e5 to the Wet diaphragm 43. The liquid regulator, including the diaphragm 43, then changes from a subatmospheric to a positive pressure liquid regulator.

As the result of the signal from the port 122; and the upward movement of the diaphragms, fuel begins to be discharged from the main fuel nozzle or port 95 and the fuel-air ratio begins to assume the straight line function required for good performance and the engine will respond quickly to demand for power.

As the throttle valve is opened to the wide open posi- `tion fuel is discharged from the main nozzle or port @6, the midrange port lll and the idling port lli@ at a positive pressure or atmospheric pressure so that the carburetor is then operating as a full pressure system.

It Will be apparent from the foregoing that the present system or device utilizes mass flow metering, that is the air-fuel ratio by Weight is proportional to the square root of the ratio of air pressure drop at the venturi throat, that is venturi pressure to fuel pressure drop at the nozzle orice.

It should be noted that the pressure drop across a high efficiency venturi is negligible when used at its designated air-flow value, and the incompressiblefluid-ow equation can be used for both the air and fuel flows, thus providing a sound metering system. i

i i Ys Further, due to the instantaneous response ofthe system to changes in air flow the fuel-air ratio remains constant, Whereas in a conventional carburetor when the throttle is opened for acceleration, there is a lag in fuel delivery due primarily to inertia of the fuel which in many cases makes it necessary to equip the carburetor with an acceleration pump. in the present case an acceleration pump is not required.

As the throttle is moved in `the closing direction the reverse order of functioning occurs.

A fuel enrichment device or primer, indicated generally at 13d, is provided and comprises a cylinder ll3ll formed in the cover 73 which is connected to the fuel chamber 7l of the pump by means of a conduit 132, the end of said conduit connected with the cylinder 13d. is connected thereto intermediate the ends thereof at a suostantially central point. There is a check valve i3d in the connection i212, said check valve being disposed in an enlarged valve chamber 134i and permits ilow of fuel into the cylinder ll31 through conduit T132 but prevents reverse iiow through said conduit.

Fuel from cylinder 131 is discharged through an outlet passage 135 which leads to a primer nozzle, not shown, discharging into the cranlrcase 7tlg of the engine to which the carburetor is attached. Fuel is adapted to ilow from the cylinder liti into the crankcase but is prevented from return iiow by a check valve i3d disposed in a valve chamber l3'7 forming a part of the fuel discharge or outlet passage of the primer.

At the end of `the cylinder opposite the discharge end there is normally disposed a piston Mtl of any suitable material and construction, said piston being shown as formed of plastic and being cup-shaped With the open end facing the discharge end of cylinder i3d. lt is to be noted that the material of the piston is somewhat flexible and that the free edge idf slidably engages the Wall of the cylinder l3ll. Means for actuating piston Mtl comprises a stem la?. slidably disposed in a bore M3 provided therefor in the cover 7 Stern fdl. extends outwardly of said Cove-r and is provided with an enlarged head idd which comprises a pressure member engageable by the thumb, or the like, of the operator to force the piston ld@ toward the discharge end `to thereby effect a discharge of priming fuel into the crankcase. The piston is urged in the opposite direction by a spring M5 which reacts between the discharge end of cylinder 1131 and the piston lift-tl.

While the primary function of the primer i3@ is to discharge fuel into the crankcase of the engine to thereby enrich the fuel mixture delivered to the engine cylinder or cylinders, it is to be noted that when the piston is moved to the normal position by spring ids? fuel is drawn from the fuel chamber 'Il of the pump and also through the passage 77, filter chamber 79 and passage `7d, so that these passages and chamber are filled with fuel and there is an immediate supply of fuel to the carburetor nozzle or orices to supply the engine With a proper fuel mixture.

The invention and its attendant advantages will be understood from the foregoing description and it Will be al parent that various changes may be made in the form, construction and arrangement of the parts of the invention Without departing from the spirit and scope thereof or sacrificing its material advantages, the embodiment hereinbefore described being merely for purposes of illustration.

I claim:

l. In'charge forming apparatus:

(A) means defining an induction passage having an air inlet section and a `mixture outlet section;

(B) an insert removably disposed in the air inlet of said induction passage to define, with the adjacent portion of the induction passage, a venturi, said insert including i (a) a hollow elongated body portion, i `(b) said body having a"A curved inward `tap r,"

(c) and being oifset downwardly relative to the axis of the induction passage so that lthe most restricted part of the throat of said venturi is at the bottom `of the induction passage,

(d) said body presenting ya .streamlined exterior with the smaller end within the induction passage and the larger end spaced outwardly of the air inlet opening of the air inlet section,

(e) the outer end of said body curving outwardly,

(f) .a ange on the outer end of said body and arranged axially of said induction passage,

Y (aa) said flange extending radially outwardly and normal to the axis of the body,

(bb) but offset from the body axis so as to be eccentric relative to the body with the wider part of the flange at the top .and the smaller part at the bottom,

(cc) the diameter of said ilange being somewhat greater than the diameter `of the air inlet or" the induction passage;

(g) means for positioning the insert within the induction passa-ge, comprising' (aa) a plurality of radially arranged and yspaced vanes on the body,

(bb) said vanes extending longitudinally of the body and hence lengthwise in the induction passage yand spaced substantially 120 apart,

(cc) the outer ends of said vanes being joined to said ange,

(dd) ythe major portion of each vane extending within t-he induction passage,

(ee) said vanes having shoulders enga-geable with the edge portion of the air inlet to limit inward movement of said insert,

(ff) a throttle stop extending inwardly from the inner end of the body of the insert;

(h) means releasably securing said insert in said induction passage;

(C) a butterfly throttle valve operably mounted in the induction passage downstream of the insert,

(a) said throttle stop extending into the patli of the trailing edge of said throttle valve;

(D) fuel supply means, including (a) a first movable wail, defining a fuel chamber (aa) having a fuel inlet;

(E) signal sensing means, including a second movable,

Wall,

(a) defining a signal pressure sensing chamber connected with the most restricted part of the venturi throat;

(F) means operably interconnecting said movable walls;

(G) and means controlled by the .rst movable wall `for controlling the inilow of fuel into said fuel chamben'said induction passage having (a) ra main fuel port,

(b) a midrange fuel port,

(c) and an idle fuel port,

(d) said ports being connected with said fuel chamber,

(e) said ymain fuel port being adapted to discharge fuel into the induction passage between said venturi throat and the throttle valve,

(f) said midrange port being between said main port and the throttle valve,

(g) and said idle fuel port being adapted to discharge idling fuel into the induction passage downstream of and closely adjacent to said throttle valve.

Z. In charge forming apparatus:

(A) means defining an induction passage having an air inlet section and a mixture outlet section;

y(B) an insert removably disposed in the air inlet of saidinduction passage to define, with the adjacent portion of the induction passage, a venturi, said` insert including y(a) a hollow elongated inwardly tapering body portion,

(b) said body being offset downwardly relative to the axis of the induction passage so that the throat yof said venturi is smaller at .the bottom `of the induction passage,

(c) said body having its smaller end within the induction passage `and the larger end spaced Ioutwardly of the .air inlet opening of the air inlet section,

(d) a flange on :the outer end of said body,

(e) arranged axially relative to said induction passage,

(aa) said flange being offset from the body axis so as to be eccentric relative to said body,

(bb) the dia-meter of said llange being somewhat greater .than the diameter of the air inlet of the induction passage;

(f) means for positioning the insert within the induction passage comprising (aa) a plurality of vanes on the body spaced substantially 120 apart,

(bb) said vanes extending lengthwise in the induction passage,

(cc) the outer ends of said vanes being joined to said flange,

(dd) means limiting inward movement of said insert,

(g) means releasably securing said insert in said induction passage;

(C) a throttle valve operably mounted in the induction passage downstream of the venturi;

(D) means, including a first movable Wall, defining a fuel chamber having a fuel inlet;

(E) means, including a second movable wall, defining a signal pressure sensing chamber connected with the smallest part of the venturi throat;

I(F) lieans operably interconnecting said movable wa s;

(G) and means controlled by the first movable wa-ll for controlling fthe inliow of fuel into said fuel chamber,

(H) said induction passa-ge having (a) Ia main fuel port,

(b) a midrange fuel port,

(c) and an idle fuel port,

(d) said ports being connected with said fuel chamber,

(e) said main fuel port being adapted to discharge fuel into the induction passage between said venturi yand the throttle valve,

(f) said midrange port being .between said main port and the throttle valve,

(g) and said idle fuel port being adapted to discharge idling fuel into the induction passage downstream of and closely adjacent to said throttle valve.

3. In charge forming apparatus:

(A) means defining an induction passage having an air inlet section and a mixture outlet section;

('B) an insert removably disposed in the air inlet of said induction passage to define, with the adjacent portion of the induction passage, a venturi, said insert including '(a) a hollow elongated inwardly tapering body portion,

(b) said body being offset relative to the axis of the induction passage so that :the throat of said venturi is smaller at one part of the induction passage, Y

(c) said body having its smaller end, within the induction passage and the largerrend spaced 9 outwardly of the air inlet opening .of the air inlet section, :(d) a flange on the outer end of said body, (e) arranged axially relative to said induction passage,

(aa) `said ange -being oifset from the body .axis so `as to be eccentric relative to said body, (bb) the diameter of said iange being somewhat greater than the diameter of the air inlet olf the induction passage; (f) means for positioning the insert within the induction passage comprising (aa) `a plurality of vanes on the body spaced annularly apart, (rbb) said vanes extending lengthwise in .the induction passage, (icc) the outer ends of said vanes being joined to said flange (dd) means limiting inward movement of said insert, (g) means releasably securing said insert in said induction passage; (C) a throttle valve openably mounted -in the induction passage;

l@ (D) said induction passage having (la) a main fuel por-t, (b) a midrange fuel port, (c) and an idle 4fuel port; (E) and means for supplying fuel to said fuel ports.

Retter-ences Cited bythe Examiner UNITED STATES PATENTS 972,571 `10/10 Pogue. 1,472,600 Il0/f23 Perris 261-65 2,393,112 1/46 Lincoln 55-418 2,713,854 7/55 Conover. .2,774,582 l1:2/56 Bracke 261-41 2,841,872 7/58 Phillips 261-41 2,843,098 7/58 Bolze. 2,926,694 3/60 Price 261-37 2,984,465 5/61 Hezza'rd 261-37 3,043,572 7/762 Ott et al. 261--52 FOREIGN PATENTS 577,770 5/46 Great Britain. 713,670 8/54 Great Britain.

`Huntelaar L. MARTIN, Examiner. 

3. IN CHARGE FORMING APPARATUS: (A) MEANS DEFINING AN INDUCTION PASSAGE HAVING AN AIR INLET SECTION AND A MIXTURE OUTLET SECTION; (B) AN INSERT REMOVABLY DISPOSED IN THE AIR INLET OF SAID INDUCTION PASSAGE TO DEFINE, WITH THE ADJACENT PORTIONN OF THE INDUCTION PASSAGE, A VENTURI, SAID INSERT INCLUDING (A) A HOLLOW ELONGATED INWARDLY TAPERING BODY PORTION, (B) SAID BODY BEING OFFSET RELATIVE TO THE AXIS OF THE INDUCTION PASSAGE SO THAT THE THROAT OF SAID VENTURI IS SMALLER AT ONE PART OF THE INDUCTION PASSAGE, (C) SAID BODY HAVING ITS SMALLER END WITHIN THE INDUCTION PASSAGE AND THE LARGER END SPACED OUTWARDLY OF THE AIR INLET OPENING OF THE AIR INLET SECTION, (D) A FLANGE ON THE OUTER END OF SAID BODY, (E) ARRANGED AXIALLY RELATIVE TOSAID INDUCTION PASSAGE, (AA) SAID FLANGE BEING OFFSET FFROM THE BODY AXIS SO AS TO BE ECCENTRIC RELATIVE TO SAID BODY, (BB) THE DIAMETER OF SAID FLANGE BEING SOME, WHAT GREATER THAN THE DIAMETER OF THE AIR INLET OF THE INDUCTION PASSAGE; (F) MEANS FOR POSITIONING THE INSERT WITHIN THE INDUCTION PASSAGE COMPRISING (AA) A PLURALITY OF VANES ON THE BODY SPACED ANNULARLY APART, (BB) SAID VANES EXTENDING LENGTHWISE IN THE INDUCTION PASSAGE COMPRISING (CC) THE OUTER ENDS OF SAID VANES BEING JOINED TO SAID FLANGE (DD) MEANS LIMITING INWARD MOVEMENT OF SAID INSERT, (G) MEANS RELEASABLY SECURING SAID INSERT IN SAID INDUCCTIONN PASSAGE; (C) A THROTTLE VALVE OPERABLY MOUNTED IN THE INDUCTION PASSAGE;; (D) SAID INDUCTION PASSAGE HAVING (A) A MAIN FUEL PORT, (B) A MIDRANGE FUEL PORT, (C) AND AN IDLE FUEL PORT; (E) AND MEANS FOR SUPPLYING FUEL TO SAID FUEL PORTS. 